Continuous emission monitoring systems (CEMS)

To protect our environment and reduce levels of air pollution, the importance for industries to monitor and control emissions is rapidly increasing. To do this and adhere to local and international legislations, Continuous Emission Monitoring Systems (CEMS) need to provide the necessary analysis for reporting functionalities such as warnings and alerts when emission limits of certain elements approach unacceptable levels.

What is a Continuous Emission Monitoring System (CEMS)?

A Continuous Emission Monitoring System (CEMS) is a system for monitoring the emissions into the air by measuring concentrations of certain substances or chemicals. This done by taking and analysing samples at regular intervals.

What can be monitored?

The answer – almost anything.

Chemicals such as:

• SO2 (Sulfur Dioxide)
• NOx (Nitrogen Oxide)
• CO (Carbon Monoxide)
• CO2 (Carbon Dioxide)
• THC (Tetrahydrocannabinol)
• O2 (Dioxygen)
• Mercury
• Hydrogen Chloride

For more information visit this link on Pollutants.

Also:

• Fuel flows
• Dust
• Temperature
• Water vapour
• Volatile organic compounds
• Airbourne particulate matter
• Pressure
• Air flow
• Opacity

How is monitoring of these substances done?

A Continuous Emission Monitoring System (CEMS) usually includes:

• Analysers to measure concentration of certain substances such as those listed above
• Equipment to sample of the emission from chimneys, pipes etc to the analysers
• Equipment/processes to remove certain element. e.g. water from the sample (if necessary) which may interfere with analytical readers
• A calibration system (a system to compare measurements delivered by a device under test conditions against known accepted standard measures)
• A Data Acquisition and handling system (DAHS) to collect and store data from the analysers which are used in complex mathematical equations to calculate the total mass emissions

The CEM system continuously runs 24 x 7, collecting data, recording, reporting even when the equipment being monitored is turned off. For example - maintenance.